The Removal And Recycling Of Heavy Metal Ions By Ion Liquid Regenerated Hydrogel

In this study,ionic liquid regenerated cellulose hydrogel and cellulose/feather composite hydrogel were prepared with wheat straw and chicken feather as raw materials and ionic liquid as solvent,which were respectively used for adsorption and removal of heavy metal ions Cd(?),Cu(?)and Ni(?)in water bodies.On this basis,with the help of the unique network structure of hydrogel,the adsorbed heavy metal ions are in-situ transformed into new nano-metal materials CdS.CuS and Ni0,which were then used for the degradation of pollutants in wastewater and catalytic reduction of hydrogen,so that achieved the reuse of metal ions.The main contents and conclusions are as follows:1.The adsorption property and mechanism of straw cellulose hydrogel ball(SCHBs)by ionic liquid on Cd(?)was studied as the adsorption material.Using the template effect of hydrogel.SCHBs loaded with Cd(?)was in-situ transformed to cellulose hydrogel-CdS nanocomposite(SCHBs-CdS),and characterized structure performance.The results showed that the maximum adsorption capacity of this hydrogel to Cd(?)reached 96.96mg/g,which was consistent with Langmuir adsorption isotherm model and secondary kinetic model.The adsorbed Cd was transformed in situ at different temperatures and times.SEM and TEM analysis showed that CdS nanoparticles(particle size 5-20 nm)had been successfully synthesized and dispersed evenly in the hydrogel.When the precipitation temperature was 50?,the time was 6 h.and the cadmium/sulfur ratio was 1:1.the photocatalytic rate of the prepared SCHBs-CdS composite was the fastest,the removal rate of methylene blue reached 100%after 4h illumination and the photocatalytic removal rate of methylene blue(MB)was still up to 90%after 5 cycles of experiments.2.The regenerated cellulose/feather hydrogel(SC/CFHBs)with different proportions of straw cellulose and feather(7wt%+2wt%.7wt%+3wt%,10wt%+3wt%.10wt%+2wt%)was synthesized by means of ionic liquid,and used for adsorption of Ni(?)in water bodies.The effects of different conditions(pH,temperature,initial concentration of metal ions)on adsorption were investigated.The results showed that 10wt%+2wt%SC/CFHBs had the best adsorption effect on Ni(?).When the temperature was 3 13K and pH was 6,the maximum amount of adsorption could reach 230.15mg/g,which was more consistent with the Langmuir adsorption fitting model and the second-order adsorption kinetic fitting model.The adsorbed Ni(?)was reduced to in situ nanometer zero-valent nickel by sodium borohydride solution,and chloramphenicol was taken as the degradation target to explore the effects of different reaction conditions(reaction temperature.NaBH4 amount and catalyst dosage)on the degradation rate of chloramphenicol and the performance of hydrogen production by sodium borohydride.Through SEM,TEM and other characterization analysis,Ni(?)was successfully reduced in situ,and the particle size was 5-50nm and evenly dispersed on the surface of the hydrogel.Experimental results show that at 30?,NaBH4 quantity is 0.3 g,catalyst dosage is 0.35 g chloramphenicol degradation rate is the fastest,the highest production rate,catalyst recycle after 5 times of catalytic activity was 71.5%,the hydrogen conversion rate was 87.8%.the removal rate of chloramphenicol was 72.9%,the store after 15 days of catalytic activity can still reach 70.3%,hydrogen conversion rate could reach 77.2%.removal rate of chloramphenicol can still reach 70.9%.3.The SC/CFHBs with different proportions of straw cellulose and feather was synthesized by means of ionic liquid,and used for adsorption of Cu(?)in water bodies.The effects of different conditions(pH,temperature,initial concentration of metal ions)on adsorption were investigated.The results showed that 10wt%+2wt%SC/CFHBs had the best adsorption effect on Cu(?).When the temperature was 313K and pH was 6,the maximum amount of adsorption could reach 178.03mg/g.which was more consistent with the Langmuir adsorption fitting model and the second-order adsorption kinetic fitting model.The adsorbed Cu(?)was precipitated into CuS by sodium sulfide solution in situ and calcined at 800? for 2 h to obtain CuS with more stable crystal and better photocatalytic performance.Furthermore.2.4-dichlophenol was used as the degradation target to explore the influence of CuS@C-N on photocatalytic performance.According to the characterization analysis,the hydrogel turned into N-doped C particles,and CuS nanorods were successfully prepared and evenly dispersed.The results of photocatalytic experiments showed that under the presence of hydrogen peroxide as photogenic electron trapping agent,the electron-hole recombination rate was effectively reduced,and the photocatalytic performance of CuS@C-N was greatly improved.The removal rate of 2,4-dichlorophenol was up to 92.9%,and the photocatalytic activity was still up to 82.3%after four cycles.